The subject matter disclosed herein relates to magnetic resonance imaging. More specifically, the subject matter relates to a modular and separable architecture of the radio frequency antenna arrays, the amplifier and channel combination circuitry, and the patient support, or stabilization, devices.
As is known to those skilled in the art, a magnetic resonance image (MRI) detects the faint nuclear magnetic resonance (NMR) signals given off by protons in the presence of a strong magnetic field after excitation by a radio frequency signal. The NMR signals are detected using antennae, commonly referred to as “coils.”
Antennae are configured to send signals to the host MRI scanner that enable trained practitioners to make appropriate diagnoses of an anatomical region of interest. For effective imaging, the antennae and their housing take on different shapes due to the shape of the anatomical region of interest. For example, the shape of a housing to fit over a shoulder is necessarily different than the shape of a housing used to image a foot. Similarly, the antennae and housings need to adapt for variations in the size of a particular anatomical region. For example, the same housing sized to fit a pediatric torso will not fit the torso of a large adult. As a result, the antennae and their corresponding housings must be designed to accommodate a broad range of anatomical regions of varying sizes, and imaging centers are required to invest in a significant number of coils to cover all imaging applications. Therefore, it would be desirable to provide an imaging system that reduces the number of sizes and configurations of housings required while servicing the same or an increased breadth of imaging applications.
Patient comfort and stabilization of the anatomy are important while obtaining an MRI because the procedures may last for tens of minutes and require the patient to remain still to prevent motion induced artifacts from appearing in the images. Historically, the antenna housing has served a dual role of stabilizing the anatomical region of interest and providing a support structure for the antennae and their associated electronic components. To assist with patient immobilization, housings have been formed from a rigid plastic to conform to different anatomical regions of interest. To assist with patient comfort, the housings may also include a layer of padding, such as foam, mounted on the support structure at points where the support structure contacts the patient.
However, requirements for designing the housing for patient comfort and for stabilizing the region of interest are often at odds with the requirements for improving the reception of the antennae within the housing. Because the sensitivity of an antenna to the NMR signals transmitted by the body decreases as the separation between the antenna and the body increases, it is desirable to place the antennae as close as possible to the anatomical region of interest, obtaining as high of a signal to noise ratio (SNR) as possible. However, design considerations for the housing to achieve patient comfort and stability impose practical limitations on how close the antennae may be placed to the anatomical region of interest. Therefore, it would be desirable to provide an imaging system that places the antennae close to the anatomical regions of interest without comprising patient comfort and stabilization.
Serviceability of an antenna is another important consideration for selecting an imaging system. If one of the antenna loops or other electrical component in a housing configured for a specific anatomical region were to fail, this housing and the enclosed electrical components must typically be returned to the vendor for repair. Due to the expense of each housing, an imaging center will often have only one of any particular size or configuration of housing. As a result, the imaging center loses revenue and must reschedule patients that would otherwise require that housing during the time it is out for repair. Therefore, it would be desirable to provide an imaging system with modular components at a low enough cost that spare parts may be kept on hand and readily exchanged in the event a component fails.
The ability to upgrade is still another important consideration when selecting an imaging system. The technology for MRI systems is constantly evolving with a trend towards higher channel count and more simultaneous imaging channels. The increased number of channels provides benefits, such as increased parallel imaging, faster scans, and images with higher signal to noise ration. Present imaging systems may have sixteen, thirty-two, sixty-four, or even ninety-six channels, with higher numbers of channels being planned. With the existing antenna and housing structures, the housings need to be upgraded as MRI scanners with higher channel counts are introduced to fully utilize the increased capabilities of the new MRI scanner. Therefore, it would be desirable to provide an imaging system which is scalable so that extra channels may be added as the capabilities of the MRI scanner allow.